• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.464-466
• /
• 2004

This paper proposes a method to consider an aging failure probability and survival probability of power system components unlike uses only aging failure probability in existing mean life calculation. The estimates of the mean and its standard deviation is calculated by using Weibull distribution and each estimated parameters is obtained from Data Analytic Method (Type II Censoring). The parameter estimation using Data Analytic Method is simpler and faster than a traditional calculation method. This paper shows how to calculate the mean life and its standard deviation by the proposed method and illustrates a exactness using real historical records of generator utilities in korea.

• Journal of Chest Surgery
• /
• 제24권7호
• /
• pp.656-662
• /
• 1991

endocarditis, 1.475% /pt-yr, overall valve failure, 3.319% /pt-yr; and primary tissue failure, 1.475% /pt-yr. The actuarial probability of survival was 94.3$\pm$3.6% and the probability of freedom from thromboembolism 90.6$\pm$4.6% at 11 years after surgery respectively. And, the probability of freedom from primary tissue failure was 60.4$\pm$16.9% also at 11 years The evidence of possible premature and accelerated failure of the pericardial valve in the aortic position among the young population was not clear on the age-related analysis of the structural failure, and no suggestion could be made to indicate age limit when the use of the pericardial valve would better be avoided.

• Journal of Korean Neurosurgical Society
• /
• 제41권4호
• /
• pp.217-223
• /
• 2007

Objective : The apparent increase in the incidence of the intracranial meningiomas in the elderly is due in part to improved diagnostic tools and improved span of life. The authors carried out a retrospect study to validate the use of the Clinical-Radiological Grading System [CRGS] as a clinical tool to orientate surgical decision making in elderly patients and to explore prognostic factors of survival. Methods : From January 1997 to January 2006, the authors consecutively recruited and surgically treated 20 patients older than 65 years of age with radiologic findings of intracranial meningiomas and a preoperative evaluation based on the CRGS. Results : High CRGS score was associated with a higher probability of good outcome [p=0.004] and a lower probability of postoperative complications [p=0.049]. Among the different subset items of the CRGS score, larger maximum tumor diameters [$D{\geqq}4cm$] and the presence of a severe peritumoral edema were associated with incidence rate of postoperative poor outcome and complications [p<0.05]. Additionally, the critical location of the tumor was also correlated with poor outcome [p<0.05]. Conclusion : A CRGS score higher than 13 is a good prognostic indication of survival. The CRGS score is a useful and practical tool for the selection of elderly patients affected by intracranial meningiomas as surgical candidates.

• Journal of Chest Surgery
• /
• 제26권1호
• /
• pp.24-31
• /
• 1993

The long term clinical results following valve replacement with Hancock and Carpentier-Edwards bioprostheses were compared between tow valve models and between tow groups totaling 249 patients who were discharged after valve replacement from 1976 to 1986. The two groups of patients were treated with nonrandomized fashion. Follow-up was 87% complete. Cummulative duration of follow-up was 1909 patient-years, with maximum follow-up duration of 15 years. The actuarial survival for 122 patients with Hancock valves was 95.2%[\ulcornerstandard deviation] and 84.4% after 5 and 10 years of follow-up, respectively. Comparable figures for 127 patients undergoing valve replacement with Carpentier-Edwards valves were 87.3% and 76.4%, respectively[p=NS]. The probability of freedom from structural valve deterioration after 5 and 10 years of follow-up was 97.2% and 60.6%, respectively, with Hancock valves and 97.2% and 55.7%, respectively, with Carpentier-Edwards valves[p=NS]. Considering all 249 patients, multivariate [Cox model] regression revealed that ejection fraction was only significant predictor of structural valve deterioration. The probability of freedom from thromboembolism after 5 and 10 years of follow-up was 91.3% and 86.4%, respectively, with Hancock valves and 94.2% and 82.5%, respectively, with Carpentier-Edwards valves[p=NS]. Hence more strict control of anticoagulation should be done on patients with left atrial factors. In summary, there were no significant differences in actuarial survival rate and major valve related complications between tow valve models. These results suggests that its use should be confined to older patients or patients with a contraindication of anticoagulation.

• 한국해양공학회지
• /
• 제35권2호
• /
• pp.161-171
• /
• 2021

For the fatigue design of offshore structures, it is essential to understand and use the S-N curves specified in various industry standards and codes. This study compared the characteristics of the S-N curves for five major codes. The codes reviewed in this paper were DNV Classification Rules (DNV GL, 2016), ABS Classification Rules (ABS, 2003), British Standards (BSI, 2015), International Welding Association Standards (IIW, 2008), and European Standards (BSI, 2005). Types of stress, such as nominal stress, hot-spot stress, and effective notch stress, were analyzed according to the code. The basic shape of the S-N curve for each code was analyzed. A review of the survival probability of the basic design S-N curve for each code was performed. Finally, the impact on the conservatism of the design was analyzed by comparing the S-N curves of three grades D, E, and F by the five codes. The results presented in this paper are considered to be a good guideline for the fatigue design of offshore structures because the S-N curves of the five most-used codes were analyzed in depth.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권3호
• /
• pp.1405-1416
• /
• 2021

The study uses an innovative management perspective to investigate the environment of higher education institutions to ensure the survival of universities in Cambodia. This has led Cambodian universities to expand their educational offerings to students in Years 2, 3 and 4. The data was collected through a Google Forms survey to facilitate and accelerate data collection. The sample of 500 students come from three higher education institution by employing multi-stage sampling technique of probability and non-probability sampling methods to ensure representation of the research population. The data were analyzed by using Confirmatory Factor Analysis (CFA) and Structural Equation Model (SEM) to investigate the impact of these determinants on students' satisfaction and loyalty, via answering 54 questions. The results showed that the three Cambodian universities perform well in terms of satisfactory conditions such as transformative quality and university image. There are four issues to which universities need to pay attention, namely, teaching methods, infrastructure facilities, learning material, and academic environment that are yet to meet the needs of students. This study contributes to the principle of innovative management in the context of Cambodian academic environment. The results help to fathom the depth of enhancing quality and institutional survival.

• 산업경영시스템학회지
• /
• 제46권4호
• /
• pp.190-198
• /
• 2023

The purpose of this study was to propose an operational concept for a ship in a fleet equipped with an interceptor missile system, a naval surface to air defense system, and to develop a simulation program that reflects it. The results of the defense activities of other ships in the fleet can be reflected by receiving information about the status of the enemy missiles. The allocation of defensive assets is based on the survival probability of the ship, not on the destruction of enemy attacks, which can be obtained as the product of the expected survival probability for each enemy missile. In addition, the concept of predicted survivability was introduced to assess the loss of future defense opportunities that would result from assigning a new command. A simulation program was also developed as a tool for realizing the proposed concept of operations, which generated cases.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권3호
• /
• pp.1039-1042
• /
• 2012

Aim: Tanscatheter arterial embolization irrespective of with or without an anticancer agent and lipiodol has been controversial with regard to survival benefit. Therefore, we conducted a prospective study to analyze the effect of transcatheter arterial lipiodol chemoembolization (TACE) on the survival of HCC. Methods: A prospective study was conducted, and a total of 326 patients with primary liver cancer who were newly diagnosed were collected from January 2004 to January 2005 in Zhejiang Provincial People's Hospital of China. A univariate Cox's regression analysis was used to assess the survival of the HCC cases receiving TACE. Results: The duration of follow-up for the HCC patients treated with TACE ranged from 3 months to 60 months. For the overall patients, survival rate at 5 years was 42%. Both HBV Ag and HCV Ab positive patients showed significantly low survival rate at 5 years. The multivariate analysis revealed The IV TNM stage was related to an heavy increased risk of death of HCC patients, and Child C grade group showed a significant moderate increased risk. Conclusion: Our study showed TACE is associated with a better prognosis of HCC patients, and the HBV infection, TNM stage, Child-Pugh grade and number of TACE may influence the survival probability. Further TACE studies should be assess the quality of life of HCC patients, so as to provide more information for treatment of HCC.

• 응용통계연구
• /
• 제34권6호
• /
• pp.957-968
• /
• 2021

역중도절단확률가중(inverse censoring probability weighting, ICPW)은 생존분석에서 흔히 사용되는 방법이다. 중도절단 회귀모형과 같은 ICPW 방법의 응용에 있어서 중도절단 확률의 정확한 추정은 핵심적인 요소라고 할 수 있다. 본 논문에서는 중도절단 확률의 추정이 ICPW 기반 중도절단 회귀모형의 성능에 어떠한 영향을 주는지 모의실험을 통하여 알아보았다. 모의실험에서는 Kaplan-Meier 추정량, Cox 비례위험(proportional hazard) 모형 추정량, 그리고 국소 Kaplan-Meier 추정량 세 가지를 비교하였다. 국소 KM 추정량에 대해서는 차원의 저주를 피하기 위해 공변량의 차원축소 방법을 추가적으로 적용하였다. 차원축소 방법으로는 흔히 사용되는 주성분분석(principal component analysis, PCA)과 절단역회귀(sliced inverse regression)방법을 고려하였다. 그 결과 Cox 비례위험 추정량이 평균 및 중위수 중도절단 회귀모형 모두에서 중도절단 확률을 추정하는 데 가장 좋은 성능을 보여주었다.

• Journal of Gastric Cancer
• /
• 제5권3호
• /
• pp.174-179
• /
• 2005

배경: 대부분의 악성종양에 있어 그 치료성적을 평가하는 가장 유용한 방법으로 가장 많이 사용되는 매개변수는 전체 5년 생존율이다. 그러나 근치적 절제술이 시행된 위암환자에 있어 재발의 대부분은 수술 후 3년 이내에 일어나므로 3년 무병 생존이 5년 전체 생존의 의미를 대치할 수 있는가를 알아보고자 한다. 대상 및 방법: 근치적 위절제술을 받고 추적이 가능한 656예에서 생존 함수로 산출한 각각의 생존확률을 이용한 단순 회귀분석에서 3년 무병 생존이 5년 전체 생존을 대치할 수 있는지를 파악하였다. 결과: 추적 기간동안 175예에서 재발이 확인되었고, 재발시기별 누적빈도는 수술 후 1년이 81예(46%), 3년이 156예(89%), 5년이 170예(97%)였다. 3년 무병 생존확률과 5년 전체 생존확률 사이의 회귀 분석결과 상관성은 r=0.87, 설명력은 $R^2=0.76$, 회귀 방정식은 5년 전체 생존확률=0.18+($0.80{\times}3$년 무병 생존확률)을 나타냈다. 복막파종, 혈행성 전이, 국소 재발의 경우 상관성과 설명력은 각각 $r=0.89\;(R^2=0.80),\;r=0.88\;(R^2=0.78),\;r=0.86\;(R^2=0.73)$으로 모두 높은 상관관계가 있음을 나타냈다. 결론: 위암환자의 근치적 위절제술 후 3년 무병 생존 확률은 5년 전체 생존확률에 대한 높은 상관성 및 설명력을 보였다. 위암의 치료성적을 평가하는 방법으로 5년 전체 생존 대신에 3년 무병 생존을 이용한다면 기간을 단축(2년)하여 평가하고 결론을 얻고 또한 보고할 수 있는 이득이 있겠다.